Version 5.1 of the Geocaching for iPhone app. was just released. And while it doesn't take advantage of the new, bigger screen size of the iPhone 5, it does include new map controls, a refined search, and Trackable image support. You can read more about it here. No word on when we can expect the next update for the Android, however.
Speaking of cool apps., here's a nice, short tutorial on how to get the most out of my favorite app., Google Maps. Designed specifically for iPhone owners who've never had the pleasure: